Dynamic optometer

Abstract

In a dynamic optometer, a variation in the direction of a subject's eye, namely, in the direction of gaze is measured by a direction detector to tilt a bi-axial rocking mirror according to the output of the detector, and an actual image of an eyeball formed by a pair of concave spherical mirrors is reflected to an optical system by the rocking mirror varying the direction of incidence. A second actual image which is formed immediately before a light source by the optical system is stably fixated in one direction, so that the eye is irradiated with light constantly from the front side in spite of eye movements. Accordingly, the refractive power can be measured, unaffected by the movement of an eyeball.

What is claimed is: 
     
       1. A dynamic optometer, which comprises: (a) a light source for irradiating a subject's eyeball with beam-like infrared light;   (b) a direction detector for detecting the direction of gaze of the eyeball;   (c) a bi-axial rocking mirror;   (d) a pair of opposingly located spherical concave mirrors, said concave mirrors being arranged with respect to said rocking mirror such that the beam-like light which passes through a point slightly deviated from the center of curvature of one of said concave mirrors and is then reflected at the center of said mirror, is thereafter passed through a point slightly deviated both from the center of curvature of said spherical concave mirror and from the center of curvature of said other mirror and then is directed toward the center of said other mirror, and an actual image of the eyeball is formed on a relecting surface of said bi-axial rocking mirror;   (e) optical system means for forming a second actual image at a position opposing said light source and optically equivalent to the eye position;   (f) a mirror rocking mechanism for tilting said bi-axial rocking mirror according to an output of said direction detector thereby to fix said second actual image irrespective of eye movement; and   (g) a refractometer for measuring the refractive power of the eyeball on the basis of positional deviation of reflected light from the fundus of the eyeball.   
     
     
       2. The dynamic optometer defined in claim 1, wherein said bi-axial rocking mirror is constituted by a single mirror rockable about two perpendicularly intersecting axes. 
     
     
       3. The dynamic optometer defined in claim 1, wherein said light source and refractometer are integrated into a light source/receiver capable of irradiating said eye with an infrared beam modulated into pulses and measuring the refractive power of said eye on the basis of reflected light from the fundus. 
     
     
       4. The dynamic optometer defined in claim 3, further comprising, between said light source/receiver and a mirror located in front of said eye, an optical system having two lenses, said bi-axial rocking mirror and two opposingly located concave mirrors. 
     
     
       5. The dynamic optometer defined in claim 3, wherein said mirror located in front of said eye reflects infrared light while passing visible light, projecting said infrared light on said eye by reflection of said mirror and permitting a subject to see a view target through said mirror. 
     
     
       6. The dynamic optometer as claimed in claim 1, wherein the two planes of incidence of the beam-like light on said spherical mirrors are perpendicular to each other. 
     
     
       7. The dynamic optometer as claimed in claim 1, wherein said direction detector comprises means for detecting a change of direction of the eyeball by detecting a reflecting light at a cornea of said eyeball with a light receiving member. 
     
     
       8. The dynamic optometer of claim 7 wherein said light receiving member is a TV camera.